异径轧制低碳钢的力学性能参数与粗糙度实验研究

通过一系列薄带异步轧制的实验，给出了压下率、轧制速度、轧件宽度及润滑条件等参数对轧制力和轧制力矩的影响．轧制力和轧制力矩随着轧件压下率、轧件宽度的增加而增加；轧制速度增加时，轧制力和轧制力矩降低；在轧件涂抹润滑剂的轧制条件下，轧制力和轧制力矩也降低．轧制完成后，薄带的表面粗糙度的值减少．同时也探讨了异径轧制过程中轧件表面的粗糙度的演变．     

不锈冷轧带钢表面光洁度的控制

在生产中，不锈冷轧带钢的表面光洁度一般用粗糙度进行控制，其粗糙度越低，光洁度越高。应使用低粗糙度和低微小缺陷面积率的不锈热轧带钢，高的总压下量，低粘度轧制油和平整率达到1％的工艺轧制可获得较高光洁度的不锈冷轧带钢。高速钢轧辊轧制的不锈冷轧带钢的光洁度优于模具钢轧辊。     

热镀锌双相钢表面粗糙问题分析与控制

 目前强度级别较高的双相钢产品已经可以普遍采用热镀锌工艺生产,热镀锌双相钢在生产过程中,表面出现明显的粗糙缺陷,形成边部与中部的色差,严重影响热镀锌双相钢产品表面质量。粗糙缺陷伴随粗糙度异常升高、锌层不均、抑制层形成不良、基板表面微裂纹等现象。分析认为,基板表面微裂纹是造成热镀锌双相钢表面粗糙的主要原因。热轧态组织和冷轧压下率是决定冷硬板浅表层微裂纹形成的关键因素。通过优化卷取温度及热轧卷厚度,改善热轧态组织及降低冷轧压下率,可有效控制冷轧板表面浅表层微裂纹的形成,从而良好解决热镀锌双相钢表面粗糙问题。     

神经网络在冷轧301S不锈钢极薄带材表面硬度预测中的应用

 基于现场生产冷轧极薄不锈钢带材表面硬度极难控制的问题,针对301S不锈钢的冷轧生产工艺进行了研究,分析了不锈钢冷轧生产过程中影响表面硬度的相关工艺参数,得出材料的抗拉强度、轧制速度、轧制油温度和压下率是影响轧后材料表面硬度的关键因素。利用BP神经网络建立了预测表面硬度的非线性映射模型,并根据此模型得出了预测数据的趋势图谱。研究结果表明,压下率的变化对冷轧不锈钢表面硬度的调节能力最强,而其他参数对硬度的影响为10HV左右。经检验,模型的预测值和实测值的相对误差为-2.63%~2.76%,预测结果准确率高,可以用于产品质量的现场在线控制。     

Thermal Scratch on Surface of SUS430 Stainless Steel Strip in Cold Rolling Process

The thermal scratch significantly influences the surface quality of the stainless steel in cold strip rolling.The thermal scratch has a close relation to the rolling parameters,the rolls surface and the emulsions used in rolling.In order to explain the thermal scratch on the strip surface,the cold rolling process of SUS430stainless steel strip was investigated in the laboratory.The thermal scratch defect occurs frequently in the second rolling pass(maximum reduction in height is 32.3%),especially on the lower surface of strips.When concentration and temperature of the emulsion are the same,the thermal scratch on the surface of the strip is aggravated with increasing the roll surface roughness.With the same roll surface roughness and emulsion concentration,the thermal scratch is obviously more severe at an emulsion temperature of 63℃than 55℃.With the same roll surface roughness and emulsion temperature,the thermal scratch is distinctly weaker at the emulsion concentration of 6%than that of 3%.     

C52100锡磷青铜冷轧断带着火原因的分析与探讨

本文通过现场观察、分析、试轧并结合轧制工艺理论的方式得出了某锡磷青铜生产企业在生产C52100时出现带材表面质量差、带材断裂以及断带着火等问题的原因。合金成分不合格尤其是硬质颗粒Pb含量偏高,以及道次压下率偏大是产生以上带材缺陷或生产事故的主要原因。同时,本文也对C52100轧制道次压下率偏大的根源即带材冷精轧时表面除油效果和除油方式不理想的现状进行了分析。     

热轧带材多缺陷和单缺陷表面质量综合预报

针对目前热轧带材表面质量缺陷类型多、产生机理不同,不能实现在线诊断的问题,提出融合各降维层深度置信网络模型的热轧带材多缺陷和单一缺陷表面质量问题综合预报技术.考虑传统深度置信网络在模型层数和节点数方面的不足,提出并建立了融合各降维层的深度置信网络模型,降低由于网络算法节点个数及层数不确定性造成的预报误差,并利用相关性将...     

二次冷轧过程工艺润滑制度综合优化技术的研究

针对以往二次冷轧生产中工艺润滑制度设定目标不全面,不能同时兼顾带材的板形、表面质量以及机组的油耗、轧制稳定性等问题,经过大量的现场试验与理论研究,充分结合二次冷轧机组的设备与工艺特点,在首次提出了一个板形油耗清洁度综合控制指标的基础上,以保证带钢板形质量、降低带钢表面残油、提高带钢表面清洁度、降低油耗作为控制目标,将打...     

热轧高强带钢氧化铁皮的去除方法

热轧板坯中添加硅元素,有利于热轧产品强度提升、制造成本降低,同时提高产品的塑性及韧性。但是,随着硅元素的添加,热轧高强带钢的生产过程中会出现典型的红锈表面缺陷。研究表明,硅与铁生成的2FeO·SiO2化合物是形成红锈的主要原因。采用常规热连轧除鳞系统(系统压力约为22 MPa)很难将红锈彻底清除,要除掉这种氧化铁皮采取超高压除鳞系统除鳞(系统压力约为40 MPa)是最为有效的办法之一。重点介绍了针对去除红锈缺陷,超高压除鳞系统在新建热连轧生产线及热连轧生产线改造中的应用。     

轧制参数对板带热轧温度分布的影响

提出了一种研究Q345钢的模型,该方法基于使用有限元法（FEM）的热机械分析。为了评估材料在轧制过程中的轧制行为,采用了有限元程序Abaqus/Explicit,并对热轧工艺进行了三维建模。考虑了传热机构的合适模型,并预测了轧制带材的温度分布和热轧带钢轧制过程中的温度变化。考虑了以下各种工艺参数的影响:轧制速度（90～210 r/min）,较高的轧制速度导致变形金属内的温度降低;压下量（5%～15%）,更高的压下量导致表面和带材中心的温度降低;带材的初始厚度（115～345 mm）,在越大的板厚度中受到的热变形影响的区域的尺寸越小;传热系数[30～50 W/（m²·K）],随着传热系数的增加,带材的表面温度和中心温度降低。     

含磷高强钢板拉矫破鳞过程的氧化皮剥离机理

为提升含磷高强钢板的拉矫破鳞效率,采用弯曲试验模拟拉矫过程中超低碳含磷高强钢板表面氧化铁皮的剥离过程,并以中点位置的压下量表征拉矫机弯曲辊的插入深度.通过表面微观检测可知,附着于带钢基体上的氧化铁皮在压应力下呈现块状剥离,拉应力下则主要表现为裂纹扩展.同时,采用ImageJ开源图像识别软件进行氧化铁皮剥离率及破裂度统计...     

非对称不锈钢/碳钢复合板可逆冷轧过程的数值模拟

应用ANSYS有限元软件分析了热轧复合的不锈钢／碳钢复合板在冷轧过程中的变形特性以及界面上的应力、应变分布，确定了界面结合强度和成卷可逆带张力冷轧时的最大道次压下量。用3D-FEM模拟了接触表面上的应力，计算出了总轧制压力，并与实验值进行了对比。对比结果表明模拟值与实验值吻合较好。     

自动板形控制技术在宝钢二次冷轧机组中的应用

介绍了自动板形控制技术在宝钢二次冷轧机组中的应用;分析了DCR机组自动板形控制系统的工作原理,给出了控制二次冷轧带钢板形的6辊轧机中间辊窜动数值计算方法,板形目标曲线设定的参数表示方法和模式表示方法,板形仪测量信号的处理过程和板形自动控制调节手段中的工作辊弯辊、中间辊弯辊和倾斜的输出值计算方法;结合生产现场运行中系统出现的问题,对改善带钢板形和表面质量提出了优化解决的方法,并在生产现场得到了验证.     

非光滑带钢在粗糙轧辊平整轧制过程中表面微观形貌的转印行为与演变规律

针对平整轧制过程不同用途带钢对表面微观形貌的特殊要求,在批量跟踪电火花毛化轧辊、磨削轧辊和冷轧后带钢表面微观形貌的基础上,建立工作辊与带钢都可考虑真实表面粗糙峰的带钢表面微观形貌轧制转印生成模型,采用工业实验验证了仿真模型的准确性,并据此模型分析轧制前带钢已经具有表面粗糙度分别大于、等于、小于轧辊表面粗糙度时,带钢表面微观形貌的轧制转印行为与遗传演变规律。提出了负转印和转印饱和的概念,定义了两种极限轧制转印状态的描述指标— —负转印最大和转印饱和,研究发现当带钢表面粗糙度小于或等于轧辊表面粗糙度时,存在负转印最大点和转印饱和点;当带钢表面粗糙度大于轧辊表面粗糙度时,负转印最大点和转印饱和点重合。在此基础上,采用负转印最大点与转印饱和点对应的临界板宽轧制力,描述带钢表面微观形貌的遗传及演变规律,并系统仿真分析带钢屈服强度、带钢轧前表面粗糙度、轧辊表面粗糙度等工艺条件参数对于负转印最大点与转印饱和点对应的临界单位板宽轧制力的影响规律,发现随着带钢屈服强度增大和轧辊表面粗糙度增加,该临界单位板宽轧制力均增大;随着带钢表面粗糙度增大,负转印最大点对应的临界单位板宽轧制力增大,但转印饱和点对应的临界单位板宽轧制力却减小。      

冷轧过程轧板内圆形夹杂物变形

运用ANSYS/LS-DYNA显示动力学有限元软件,建立了水平辊系二维五连轧弹塑性有限元模型,利用小型重启动方法对DCO3冷轧板五连轧过程中轧板内硬性夹杂物变形进行了模拟,分析了夹杂物尺寸、初始位置以及轧板压下量对夹杂物变形的影响。研究结果表明：模拟结果与实际相接近,轧板内夹杂物的变形程度主要随着轧板压下量的增加和夹杂物尺寸的增大以及夹杂物距轧件表面距离的减小而增大。轧件由3.0mm被轧到0.7mm,夹杂物直径超过20μm时,轧制结束后夹杂物前后部位处变形程度较大,轧件内部可能会产生由于夹杂物破裂而形成的裂纹源。     

Developments of work roll bite lubrication at SSAB Tunnplåt AB hot strip mill

In the strip rolling process friction is needed at first to pull the strip into the roll gap, otherwise slipping occurs. After the neutral plane however, where the velocity of the work roll equals the velocity of the strip, the friction stress alters direction to the opposite. If the friction stress after the neutral plane then is lowered, the total roll force will decrease. This can be done by a properly applicated oil- and water dispersion close to the work roll gap and between the roll cooling wipers. The technique and the key to a successful lubrication is a work roll surface which is as dry as possible. If the roll surface is not dry, neither large changes in the oil concentration, nor changes in the oil composition can make the lubricant stick to the roll surface. The lubricate was partly washed away by the water and only a small roll force decrease could therefore be measured. Only when the roll cooling water on the entry side of the work roll was set off on purpose, the roll force decrease was significant. Due to this result, further test were performed in an upstream stand in the hot strip mill. Here, the work roll wipers were modified and the roll was substituted by one with a larger radius and lubricated. The result was very slight or no water leakage at all. The roll force decrease was then much greater than before and close to those measured for the same reduction in the case of no entry water for the later stand. The electrical current in main drives and the roll wear in the lubricated stand could also be lowered significantly. In addition, the strip surface was greatly improved, under conditions with a high possibility of oxide residual contamination from the roll surface.     

Great reduction pratice of SUS304 in cold-rolling

SUS304 stainless steel is typical of austenitic stainless steel,which organization is metastable austenite,easily appears work hardening in cold rolling.According to the common process,the max reduction of cold rolling in one stage is below 80%,we try to rasie the max reduction to 90%in one stage (wecalled that "great reduction" ) from the view of cuting cost.Due to the work hardening,great reduction brings lots of problem(the difficulty of flatness control,strip break..etc)。This article analyzed the great reduction from properity of SUS304 steel,mill types,flatness control,rolling technics etc,supplied the corresponding solutions,and formed a sophisticated great reduction theory. This article focuses on the unusual thermal crown of raw materials(ie,abnormal distribution of horizontal thickness) and the rolling force fluctuations in "great reduction" rolling.First,the "distortion" phenomenon which caused by unusual thermal crown of raw materials is explained,wedge-shaped strip In coiling, because of a big difference in thickness on both sides,leads to different compressive stress on both sides of flatness roll,so that the flatness measurement is distorted;Second,the "strip shifting" phenomenon caused by wedge shape of strip is explained,we analysis the stress on both sides of the strip,concluded that the wedge-shaped strip on the coiler will shift to the thick side of the deviation,the amount of strip shifting is related to the wedge level;Because of the characteristics of SUS304,the strip is difficult to be rolled in the last few passes.so the strip breaking is easily occurred,we found the reasonable parameters(rolling speed, cooling oil,tension,etc) to solute that problem;The deviation of rolling force will cause the shape of the roll gap,thus affecting the shape control,especially in the head and tail part of the strip,It is important to minimize the deviation of rolling force;The "great reduction" process provide the favorable flatness(< 8I-unit) and thickness deviation which less than±3 um,with no significant difference between common process.In mechanical properties,the elongation of the great reduction strip is less than common products by 2%-3%,but that can be adjusted through the annealing process improvement.At present,we have been using this technology for mass production,achieving good economic benefits.     

Re-reddening on Strip Surface After Water Cooling

After water cooling,there is a big temperature difference between the center and the surface of strip,which leads to the heat transfer from the center to the surface,and the surface temperature can rise in a short time.The finite element method was used to simulate the phenomena of re-reddening on the surface of strip and to analyze the temperature field of hot rolled strip during laminar cooling,and the periodical variation curve of the cooling rate was obtained during water cooling and subsequent re-reddening.The results show that the critical line of the cooling rate is at 1/3 of the half-thickness from the strip surface.The regression model of the relation of re-reddening temperature,time,and distance from the surface was obtained in the re-reddening region.Re-reddening regularity on the surface of strip under the condition of different thickness and cooling rate was also studied.     

无取向电工钢织构的演变及其沿带钢宽度方向上的差异

采用EBSD检测技术,分析了50W800无取向电工钢在重要生产工序间织构的演变以及织构沿带钢宽度方向上的差异性。结果表明:热轧板织构沿带钢宽度方向上的差异性主要体现在表层织构。带钢边部表层织构主要由旋转立方织构、α纤维织构以及少量的γ纤维织构组成,带钢宽度1/4处的表层织构主要存在高斯织构,带钢宽度1/2处的表层织构主要为(110)面织构以及少量的铜型织构。各处的带钢宽度1/4处和1/2处的织构类型基本一致,都以α纤维织构和旋转立方织构为主。冷轧后,各处的表层织构类型差异较小,均为γ纤维织构和α纤维织构。由板宽边部至中心处织构强度值逐渐降低。退火后,各处织构的组分基本一致,为较强的γ纤维织构和较弱的(100)面织构。各处织构强度值差异较小,变化趋势与冷轧板一致。     

A Physical Based Method to Predict Spread and Shape during Flat Rolling for Real‐Time Application

A physical based method is developed that gives real‐time solutions for the transverse variations, across the strip width, for the strip stresses and strains during rolling. From this the strip spread and downstream shape defect are predicted for a given variation in the thickness reduction across the width. The method implicitly couples the downstream residual stresses of the strip under tension, due to non‐uniform strip elongations or shape, to the stress field within the roll gap. The case of a parabolic variation in thickness reduction across the strip width is investigated with the sensitivity of shape defect with the non‐uniform reduction predicted, for various strip thicknesses and widths. These results are shown to be consistent with previously published experimental results. The model is therefore useful in predicting the limits of thickness profile change during rolling before shape defects are formed. Furthermore, being an analytical method the prediction of spread and shape defects can be made in real‐time with a minimum of computational cost. The spread model is then coupled to a roll stack deflection model so that the non‐uniform thickness reduction is also calculated for a set of rolling conditions. The full model solution is calculated within several seconds on a PC, making it possible for real‐time application.